The present day worldwide web is composed of a number of interconnected data networks throughout the world. These data networks may be of a number of different types, and were developed by different providers, based on different protocols. More recently, a MPLS (multi-protocol label switching) network has been designed which allows various dissimilar data packets to be carried by the same network with the addition of new labels, which are recognized by the MPLS system, regardless of the source of the original data. Thus, the MPLS network may be connected to dissimilar networks and carry packets of data between them.
Entry points to a MPLS network are known as label edge routers. Such a router can accept traffic from different sources and thus may be connected to different networks. Data packets are assigned labels as they enter the network. These labels can provide a mechanism to group related sets of the packets together and isolate one group of packets from another. Thus, the packets are forwarded at layer 2, which eliminates the need for layer 3 forwarding between nodes. This simplifies the forwarding process and results in high speed and high performance.
Arrangements of MPLS networks are seen, for example, in U.S. Pat. Nos. 6,477,166 and 6,473,421.
The MPLS network can be used successfully by network service providers, which provide a virtual private network service for their customers. That is, the data stream can be controlled without having to stop at every node along the path by setting up an end-to-end label-switching path. However, further improvements in these networks are possible, especially in a circumstance where a system is being replaced or upgraded in order to avoid any loss of service for the customer.